Fluid pressure producing device



' 5 42 40 56 66 6'4 92 4 7 Y I 4 m I /l// X4 7 Z 5 INVENTOR. I 1 ama-wfif'wmze (I June 15, 1943. Q FOWLER, 2,322,009

FLUID PRESSURE PRODUCING: DEVICE Original Filed March 7, 1940 A ONEV Patented June 15, 1943 UNITED "STATES PATENT OFFICE.

ori inal application March 1, 1940, Serial No.

Divided and this application January 10, 1941, Serial No. 374,004 r 5 Claims.

This invention relates to master cylinders for hydraulic brake systems and moreparticularly to a compound cylinder and a method of manuiacture thereof. 1

This'application is a division of 'my pending application, Serial No. 322,790, filed March '7, 1940, and is made in accordance with the United States Patent Ofjlice Rule No. 42.

Broadly the invention comprehends a fluid pressure producing device of the two phase type of construction and the invention is designed I to standardize production and to reduce the cost of manufacture of such device.-

An object oi the invention is to provide a compound cylinder -formed of component parts.

Another object of the invention is to provide in the bore 30 base bearingized chamber 34 and a circumferentially reduced portion providing in conjunction with the wall defining the bore II. an annular passage 36 communicating with the 5 chamber 24, and a port 38 arranged in the wall oi thecylinder 32 providing a communication between the chamber 34 and the annmar-passage 36. It is also proposed to construct the cylinder section 32 as a separate unithaving a uniform" n circumference and overall length complementary to the bore 30, and a chamber 34 which may be of any one of several gauges so that any desired diflerentialin the gauge of the chamber 20 and that of the chamber 34 may-be had. This cylinl5 de r section 32 may be secured in the bore ll by apress fit, as illustrated in Figs 1 and 2, or

a doublediametral' cylinder including component pgrrttg thereoi, and a method of assembly oi the Another object of the invention is the pro- 50 vision of a cylindrical sleeve adapted to be inserted in the-cylinder of a conventional fiuid pressure producing device and thereby provide a cylinder having double diametral bores.

Other objects and advantages of the inven- .25

tion will appear from the following description taken in connection with the accompanying drawing forming a part of this specification, and

in which-.-

Fig. 1 is a sectional view 01' a compound master ($0 cylinder embodying the invention;

modification of the compound cylinder.

Referring to the drawing for more specific details of the invention, a single casting includes a reservoir IIL-having a filling opening l2 normally closed by a head I4 having openings I6 40 therethrough for venting the reservoir to the atmosphere, and a cylinder I8 at thebase-oi the reservoir having one of its ends closed as by a. head 20 provided with a discharge port 22, and its other end open. f

In the open end of the cylinder is achamber 2 of standard gauge. bearingized, and provided with spaced ports 28 and 28 affording communication between the chamber 2! and the reservoir It. The cylinder. i8 also has a bore 30, prefer- 5 ably of slightly less diameter than the chamber the cylinder may be heated and the cylinder section 32 chilled and then assembled as shown In-order to standardize production and thereby reduce cost in the manufacture of fluid pressure producing devices of this type, it is the purpose g Of the instant invention tosconstruct the reservoir l0 and the cylinder ll asa single unit. The cylinder has a standard gauge chamber 24- and a bore 30 oi uniform size forward of the chamber. The bore 30 may be of less diameter than V the chamber- 24, as shown in Figs. 1 and 2, or of the same gauge as illustrated in Fig. 3.

lmFlg. 1 the bore SI is oi reduced diameter as compared with the chamber and the cylinder section 32 has a length equal to the length of the reduced bore 30. This cylinder section is' fitted tightly in the bore III with an end. portion of reduced external diameter providing in conjunction with the immediately surrounding. wall oi the bore 30, an annular passage 36 communieating through port 38- through the wall of the cylinder section with the chamber It 'withln' the interior of the cylinder section,

In Fig. 2 the reduced diameter bore ll oi the master cylinder has a length less than the length of the cylinder section 32. The cylinder section is fitted tightly withinthis reduced diameter 5' bore and is of uniform external diameter throughout its length. The passage 36, which corresponds to the passage 38 in Fig. 1, is formed between the end portion of the cylinder section 82 and the immediately surrounding wall ofchamber 24 01 the master cylinder.

In Fig. 3 the master cylinder is of uniform internal diameter throughout its length and the cylinder section 32 is of the construction shown in Fig. ibeing provided withan end portion of reduced external diameter. Between this reits open end with a chamber 24 and adjacent" to its closed end with a chamber 34 and the chamber 34 is of reduced diameter as compared with chamber 24. Chamber 34 of reduced diameteris formed by the cylinder section 32 which is fltted tightly within the master cylinder ad jacent to its"- closed end. The chamber 34 communicates with the chamber 24 through a port 38 through the wall of the cylinder section 32, and the annular passage between a circumferential portion of section 32 and the immediately surrounding wall of the master cylinder.

A piston 40 reciprocable in the chamber 24 is retained against displacement by a washer 42 seated on the annular shoulder in the open end of the cylinder l8 and held in place by a retaining ring 44 seated in a groovein the wall of the cylinder. The-piston 48 includes a head 46, a body 48 having a reduced diameter providing. in conjunction with the wall of thecylinder l8 an annular chamber 58 communicating with the reservoir Ill as by way of the port 26, and a skirt 52 supporting a sealing cup 54 for inhibiting seepage of fluid from. the annular chamber 50 past th piston. The head 46 has a plurality of spaced passages 56 therethrough providing communications between the annular chamber 50 and that portion of the chamber 24 forward of the piston, and a sealingcup 58 seatedon the head 46 of the piston controls the passages 58.

A washer 60 seated on the end of the cylinder 32 opposite the piston 40 has in its periphery a plurality of spaced notches 62 for the passage of fluid between the chamber 24 and the annular chamber 36, and also a plurality of spaced lands 64 preferably. stamped or embossed in the body of the washer, and a'spring 8 6 interposed between the sealing -cup 58 and the washer 88 serves to retain the cup and washer against displacement and also to assist in return of the pis-' having a plurality of passages 88 therethrough providing communications between the chambers 24 and 34, ands. concentrically disposed shallow bore 90. A rubber washer 92'seated on the head 86 of the piston has a concentric opening therethrough registering with the shallow bore 98. This washer is preferably constructed from rubber having a high durometer reading. The diameter of the washer is slightly less than the gaugeof the chamber 34, so that fluid may bypass the washer when it is not under pressure. The washer 92 has a concaved face 94, and'this concaved face in conjunction with the perimeter of the washer provides a pronounced lip 86. A spacer or pressure block 98 seated, on theconcaved face of the washer has a convex face I00 complementary to the concaved face of the washer. The pressure block 98 has an extension I02 concentrically disposed on its convexed face, and this extension is received by'the opening in the washer and also by the bore 90 inthe head of the piston with small clearance between the bottom of the bore and the free end of the extension |02, so as to limit the compressibility of the washer and thus avoid binding of the washer in the chamber 34.

The pressure block 98 has a plurality of spaced passages, I04 therethrough controlled as by a sealing cup 106 seated on the pressure block. High pressure imposed on the sealing cup I" is transmitted through the pressure block 98 to the washer 88. This results in radial expansion of the washer, and because of the particular contour thereof the lip 86, when the washer is deformed under pressure, engages the wall of the chamber 34 with substantial bearing surface.

ton 40 to its retracted position.

The piston 48 has disposed concentrically in its body 48 a valve chamber 68 opening through the head of the piston, This valve chamber has a port 18 providing a communicationbetween the valve chamber and the annular chamber 5g and also a vent 12 opening from adjacent the bottom of the valve chamber into the annular .f

chamber 58 for inhibiting fluid look; A valve 14 slidable in thevalve chamber abuts a compression spring ,16 of high elasticity seated on the bottom of the valve chamber.

The valve includes a cylindrical body 18 fitted snugly-f0r reciprocation'in the valve chamber. This cylindrical body has a peripheral groove or slot 80 adapted to register with the port 10 in the valve chamber so as to provide for passage of fluid from the chamber 24 through the valve and into the annular chamber 50. The groove The valve 14. has a stem .82 formed integralwith a piston 84 reciprocable in the chamber 84. The piston normally seats on .the lands 84 of the washer 68., It is essential that this pis- A. two-way valve I08 seated on the head of the cylinder l8 within the chamber 34 controls the discharge port 22, and a spring H0 interposed between the sealing cup I88 and the two-way valve I88 serves to retain the cup and valve ainst displacement and also to return the pistons 48 and 84 to their retracted positions. The spring H8 is, of'high elasticity, and is preferably balanced with the spring 16 in the valve cham- A thrust pin 2 has one of its ends seated in a'socket in the back of the piston 40, and on the other end of the thrust pin is a' coupling 4 connected by a flexible boot H6 to the open end .of the cylinder l8 for the exclusion of dust and other foreign substances. A rod H8 has one of its ends connected to the coupling H4 and its other end-pivotally connected to. a foot pedal lever not shown. I

While-this invention has been described in connection with certain specific embodiments, the

, principle involved is susceptible of numerous of. the appended claims.

{.claim:

1. A master cylinder having a closed end provided with a bore and an open end, a cylinder section'fitted tightly' therein adjacent to the closed end providinga chamber at such end of reduced diameter as compared with the chamber adjacent to the open end, said cylinder section having a circumferential portionrat its end which is remote from the closed end of the master cylinder spaced from the immediately surrounding wall of the master cylinder and forming therewith an annular passage communicating with the chamber adjacent to the open end of the master cylinder, said cylinder section having a port establishing communication between said annular passage and the interior of the cylinder section. v

2. A master cylinder having a closed end provided with a bore and an open end, a cylinder section fitted tightly therein adjacent to the closed end providing a chamber at such end oi reduced diameter as compared with the chamber adjacent to the open end. said cylinder section. having a circumferential portion of reduced di-- the smaller bore, said cylinder suction having a port providing communication between the larger bore and the cylinder section.

4. A device or theclass described comprising a reservoir, a cylinder at the base thereof having a closed end provided with a discharge port and an open end, a chamber in the open end communicating with the reservoir, a chamber of relatively less diameter in the closed end and a' cylinder section squeezed in the small cham- I Mr providing in conjunction with the wall of the cylinder an annular passage communicating with the large chamber and a port in the body portion of the cylinder section providing a communication between the annular passage and the cylinder section. i a

5. A device of the class described comprising a cylinder having axially disposed concentric bores, the large bore defining a chamber, and a cylinder section in the small bore extended partially into the large boreto provide in conjunction therewith an annular passage, said cylinder section defining a chamber of smaller diameter than the chamber in the large bore and having a port oi its wall providing communication between the chambers by way of the annular passage.

OWEN H. FOWLER. 

